This invention relates to apparatus for sorting objects according to both size and colour. While the apparatus was designed primarily for sorting fruit, and in particular tomatoes, it could be used for sorting other objects of varying size and colour.
A number of sorters based on optical principles are known in the prior art but none appear to offer the capability of sorting into a large number (e.g. fourteen) of size/colour categories while using only two photosensors as in the present invention. For example U.S. Pat. No. 3,097,774 of J. F. Hutter et al., issued July 16, 1963, discloses apparatus for sorting ore fragments according to reflectance characteristics of the ore but it apparently only makes a binary sort. That is, a particle is either accepted or rejected.
U.S. Pat. No. 3,380,460 of F. Fuis, Jr., et al., issued Apr. 30, 1968, discloses apparatus for sorting tobacco leaves and sheet metal. A relatively large number of photocells are required to measure the length of a leaf.
U.S. Pat. No. 3,382,975 of M. C. Hoover, issued May 14, 1968, relates to apparatus for sorting potatoes. Colour is not measured. A comparison is made as to whether the object is lighter or darker than a standard.
U.S. Pat. No. 3,854,586 of Perkins, III, issued Dec. 17, 1974 discloses a complicated system for sorting objects such as tobacco leaves on the basis of colour only, no measurement of size being made.